What used to be a decision between whole, low fat, and skim is now a choice between whole, low fat, skim, lactose-free, flavored, organic, conventional, soy, and milk made without artificial hormones.

The dairy aisle has grown increasingly cluttered with options – and state lawmakers are now wrestling over labeling one of those options: Milk made without recombinant bovine growth hormones (rBGH).

The synthetic hormone – linked by some to health problems in humans when ingested – artificially reproduces a naturally occurring hormone found in dairy cows. It's produced by Monsanto Corp. and sold under the name Posilac. Dairy farmers administer Posilac to lactating cows to increase yields. Its use is banned in Europe and Canada, but the US Food and Drug Administration approved the use of the artificial hormone in 1993.

In tandem with the rise in organic milk sales, more dairies, supermarket chains, and retailers are offering milk from untreated cows. Because there are no commercially available tests for the artificial hormone, dairy farmers sign affidavits stating they do not use Posilac. Along with dairy processors, this year Starbucks, Kraft, and Wal-Mart rolled out rBGH-free milk products.

"For marketers and processors this is a way to present 'quasi-organic' or 'organic lite' products and extract a premium from consumers," says Chris Galen, a spokesman for the National Milk Producers Federation in Washington, which represents conventional dairy marketing cooperatives. The rBGH-free label used to offer a competitive edge; now it merely serves to keep marketers up with the times. "It's the old joke about why did the chicken cross the road? Because it can," Mr. Galen says.

Sales of milk labeled "artificial hormone-free" do not appear to be affecting the organic market, says Eric Newman, a representative at Organic Valley, a cooperative that sells milk under the Organic Valley and Stonyfield Farm labels. But many in the dairy industry see Wal-Mart's recent decision to sell rBGH-free milk as a bellwether. "It'll probably put the death knell to synthetic growth hormone," Mr. Newman says.

What also remains strong is state-level debate over labeling, which ap­­pears to be reaching a peak. Pennsylvania, the fifth-largest dairy state, essentially banned labeling claims in October 2007, but rescinded the ban after considerable consumer backlash. Ohio, Missouri, Kansas, Indiana, and Michigan all have pending legislation or rule changes that would limit labeling claims about hormones.

Some say Monsanto is behind attempts to remove mentions of hormones. "Clearly what's going on is Monsanto is trying to get states to thwart the market from working," says Michael Hansen, senior scientist for Consumers Union. "If the market wants blue corn and not yellow, and people want blue, that's the way the market works."

Many consumers appear to favor milk without Posilac – marketed under both organic and artificial hormone-free labels. But Monsanto contends that milk from cows treated with Posilac is safe and no different from milk from cows with naturally occurring hormones. They say labeling claims about hormones mislead consumers into thinking there is a difference in milk quality.

Furthermore, Monsanto spokeswoman Lori Hoag says that farmers decrease their profits by not treating cows with Posilac. "It makes [cows] more efficient and productive," she says. "In general, the producers are not getting compensated for the ability not to use that product."

Maine dairy processor Stanley Bennett, of Oakhurst Dairy, contests that statement. He was the first bottler to tout rBGH-free milk. "In addition to premiums to not use growth hormone," he says, "there are basic incentives for a dairy farmer to 'go off the needle.' They relate to wear and tear on the animal." Poor management can lead to health problems in cows treated with rBGH, he says.

Among dairy farmers, though, there's no consensus about the bottom line. "There's a place for it on some farms, but not my farm. It's because of our values," says Angie Facey, a farmer and co-op manager at Our Family Farms, a small distributor of rBGH-free milk in western Massachusetts. "A high-producing cow has to be a healthy cow. I honestly don't think it hurts the cow."

Monsanto has unsuccessfully petitioned the Federal Trade Commission for a rule change about what it says is deceptive labeling. Other legal action taken by the company and lobbying by farm bureaus to block such labeling has largely failed. Legal precedent appears to uphold the free-speech interest of dairies and the consumer's right to know.

But Monsanto's Ms. Hoag says the company has no plans to pull Posilac. "We continue to hear from producers that this is a profitable product they can use."

As other new agricultural technology reaches the market, labeling debates appear likely to increase, industry analysts say. For example, milk made from cloned animals and their offspring, approved Jan. 15 by the FDA, has already prompted one labeling bill in California.

In addition, cheese and other products made with milk have not faced the same level of labeling scrutiny that milk has. "This issue will not go away," says the Consumer Union's Mr. Hansen.

Organic vs. hormone-free

Consumers strolling by the dairy aisle at their local grocery story may wonder: What's the difference between organic and hormone-free milk?

The US Department of Agriculture has established rules so you can know the answer.

USDA regulations for organic milk prohibit the use of artificial growth hormones and antibiotics while mandating that cows are given access to pasture and fed organic grains.

Dairies that produce and market hormone-free milk have essentially agreed to abide by just one of the principals of organic milk production.

While organic dairy farmers are required to be inspected by independent third parties who verify a farmer's compliance, artificial hormone-free dairy farms are not inspected. In most cases those farmers sign a legally binding affidavit instead.